The UN says it has received reports that guards fired on migrants who tried to flee air strikes on a detention centre near Libya’s capital Tripoli on Tuesday.
The UN says it believes at least 53 migrants died and 130 were hurt in the air strikes on the Tajoura centre.
UN High Commissioner for Human Rights Michelle Bachelet has said the air strikes could constitute a war crime.
The government and an opposing militia have blamed each other for the attack.
Thousands of migrants trying to reach Europe, many of them sub-Saharan Africans, are being held in Libyan detention camps. Dozens who set off from Libya were feared dead as a boat capsized off Tunisia on Wednesday.
Libya has been torn by violence and division since long-time ruler Muammar Gaddafi was deposed and killed in 2011.
A recent upsurge in violence began in April when the self-styled Libyan National Army (LNA), commanded by Gen Khalifa Haftar, launched an offensive against the UN-backed Government of National Accord (GNA), led by PM Fayez al-Sarraj.
A UN mission visited the camp on Wednesday and helped evacuate the injured but said there had been “no general relocation of the remaining refugees and migrants” and that some 500 people faced “the same degree of vulnerability and exposure to violence”.
BBC
